Related art iris recognition devices, which lack appropriate mechanisms to compensate for pupil size variations in response to changes in intensity of lighting, tend to have poor iris recognition accuracy owing to changes in iris images caused by pupil size variation.
As a related art technique, a patent application filed by the applicant of the present invention and disclosed in Korean Patent Laid-Open Gazette No. 10-2006-81380 provides an invention that is related to the present invention but differs in terms of subject matter. The related art invention relates to a mobile terminal having a stereo camera that is configured to capture images suitable for face recognition and/or iris recognition. The stereo camera is used to compensate for image size differences in consideration of the distance between the face and the camera. However, the related art invention deals with subject matters different from those of the present invention, and may increase device volume and cost owing to mounting of a stereo camera.
A patent application disclosed in Korean Patent Laid-Open Gazette No. 10-2002-28146 provides another related art technique, in which the pupil radius changing according to brightness of lighting is divided into one or more classes. Multiple iris images of individual persons are classified according to pupil radius classes and stored for enrollment, and an iris image captured for identification is compared with enrolled iris images. Although this related art technique is similar to the present invention in use of pupil radius, it fails to provide a means for efficiently utilizing identification information and iris size information stored in iris images, imposing restrictions on improvements in iris recognition accuracy and processing speed.